shit is pretty cheap from local chemist, buy the tablets to keep with you when youre on the run out and about and buy the liquid for at home use. You can use the liquid to add to a shit ton of milk and you have to leave it for about 24 hours so it converts all the lactose.
By the way I would also make note of anyone that isnt truly lactose intolerant taking these enzymes can actually down regulate your own production of lactase. So just be sure its an allergy to lactose and not an allergy to some of the proteins contained in diary products.